


Imperative

by nhpw



Category: Supernatural
Genre: Alpha Castiel, Alpha/Beta/Omega Dynamics, Dubious Consent, Extremely Dubious Consent, M/M, Mating Cycles/In Heat, Omega Dean Winchester, Season/Series 11, Season/Series 11 Spoilers
Language: English
Status: Completed
Published: 2016-02-07
Updated: 2016-02-07
Packaged: 2018-05-18 18:04:44
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,649
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5937898
Author URL: https://archiveofourown.org/users/nhpw/pseuds/nhpw
Summary: <blockquote class="userstuff">
              <p>“I don’t want to do it when you’re in heat,” he’d explained when Dean had asked about it a few months back. “You’re… not yourself, then. It’s not you talking. It’s your biological imperative to mate and breed. So no. I won’t claim you until you ask me to do it outside of that loop.”</p><p>But suddenly Castiel wants to go back on his promise.</p><p>Something's definitely not right about Cas. Something's definitely not right at all.</p>
            </blockquote>





	Imperative

**Author's Note:**

> My first ever A/B/O fic. Be gentle! I assumed one big thing, which is that Dean can't get pregnant unless he's been bitten/claimed. IDK. It worked for the story?
> 
> ***SPOILER WARNING: "The Devil in the Details" (Season 11, Episode 10) is ABSOLUTELY REQUIRED VIEWING*** or the plot twist will be lost on you and the story probably won't make sense. This little tidbit takes place probably between "Into the Mystic" and "Don't You Forget About Me." Assumes all/most canon details remain the same, except obviously the whole Alpha/Omega thing. 
> 
> And the "dubious consent" tag is there because I'm sure if Dean knew who he was doing the horizontal polka with, he'd revoke that consent like a hot potato. 
> 
> This won't be a series, but I *might* write a followup from Lucifer's POV. Maybe. Someday.

“Please, Cas.  _ Please _ .” Dean hates this. He hates how fucking needy he gets when his heat comes on. Hates that all of the physical strength and emotional checkpoints he’s spent his entire life counting on don’t mean a damn from the moment he feels that tingle at the base of his spine. He starts to sweat not long after, and then the slick starts coming and it’s all over. He’s a whore until it’s over. Five days of being helpless to his hormones. Five days of heightened smells and nausea and begging for Cas’s knot.

It used to be worse, though. A lot worse. Before Cas… it was so much worse.

Now he has a mate. Well - a regular partner, at least; someone he considers his mate, and the only person whose knot he’s interested in, although the former angel has yet to sink his teeth in.

“I don’t want to do it when you’re in heat,” he’d explained when Dean had asked about it a few months back. “You’re… not yourself, then. It’s not you talking. It’s your biological imperative to mate and breed. So no. I won’t claim you until you ask me to do it outside of that loop.”

That’s the thing. Outside of his heats, Dean knows there’s no place in his life for a mate, so he doesn’t ask. The hunter’s life isn’t built for keeping ties. Doing that just puts mates and pups in danger. Better to leave it as it is - 99 percent satisfaction on both his part and Castiel’s, and outside their cycles of heats and ruts, they don’t fool around much. A few meaningful glances and lingering touches and the occasional fuck, sure, but no talks of settling down, no talks of breeding or raising pups or leaving the hunter’s life behind for something more stable. That only happens when he’s feverish and needy and panting under Cas’s ministrations.

Somewhere along the line - maybe six months ago - their cycles had synced up. Cas rutted about the same time that Dean was in heat. It made for mind-blowing sex. It also made Cas a bit of a douchebag sometimes.

“You want it, Dean? You want my cock? Prove it. Present yourself to me. Now.”

“Dammit, you’re an asshole.” But he’s moving into position even as he says it, and in two heartbeats he’s on all fours in the middle of the bed, ass up and head bowed between his arms in submission.

“Good. Good.” Cas comes over and pets his hair tenderly. Every nerve in Dean’s body is on fire and screams in agony as Cas traces a single finger down his spine from neck to tailbone, lingering over each bump of the vertebrae. “God, you’re beautiful.”

Through the hormonal fog, Dean catches something in Castiel’s tone that’s out of place. It’s not the first time he’s admired Dean’s body, but this time it sounds almost… reverent. Not like he’s reviewing something he’s studied a thousand times, but rather like he’s just come upon something completely new.

“Any time you want, Cas. Not getting any less horny here,” he says, because he thinks maybe the difference in tone is Castiel trying mightily to keep a lid on his own desires. He’s like that sometimes, not wanting to give in to the rut, not wanting to take his pleasure if Dean’s not ready. A little reassurance usually does the trick.

And this time, too, Cas slips a finger into Dean’s leaking hole and that removes any coherent thoughts from the omega’s brain. “Fuck, Cas, I’m ready, just fucking-- I need--”

“Uh uh uh,” Castiel tisks. “I know what you need, omega. And you’ll get it. All in good time, Dean. All… in good… time.” He adds another finger and Dean groans - it’s good, it’s really good, but it’s not enough.

“ _ Please _ ,” Dean whines. He feels the first tears slip out because if he doesn’t get relief soon, he’s going to be in a world of hurt - the cramps are already starting. He needs something, now, and he’d really like it to be Castiel, but if the alpha doesn’t hurry it up he’s going to have to resort to a plastic knot.

“So needy. So… helpless. Amazing.” There it is again, that tone, like this is all somehow new to Castiel.

“What the fuck, Cas?”

“Mouthy for an omega, too. We really will need to work on that.”

Alarm bells start sounding off in Dean’s brain - to signal what, he doesn’t know, but just weirdness he guesses - but then there’s a blunt cockhead against his hole, and then Cas is filling him up, and fuck, it doesn’t matter. Nothing matters. Whatever he sounds like, whatever weird shit he just said, this is Cas. He feels like Cas and smells like Cas and fucks just. Like. Cas. Deep, and hard, and filling Dean up to satisfy his omega biological imperative to surrender and breed.

“What do you think, Dean? Is tonight the night, hmmm?” Through the haze, Dean vaguely hears those warning bells again as Cas starts sniffing decisively around his neck. There’s a lick to his jugular - not gentle kisses, but a lick, slow and purposeful. Like he’s scouting out a spot.

“Nnn…” Dean grunts, shaking his head. “Not tonight,” he manages. “Not while I’m in heat. That’s what you said.”

Cas pulls away from his neck then, but Dean doesn’t miss the almost regretful sigh. “Of course. Still gonna knot you though. Fill you with my seed. You ever think about it… hmmm… the fallen angel, the former vessel of heaven… what great empires our pups could build? How powerful they might be when they came of age?”

“All the damn time, Cas. Fuck.” He feels Castiel picking up the pace and starts rocking back to meet his thrusts, but a hand on his back stills him.

“Stop that, omega. You take what I give you,” Castiel growls, and fucks harder still, but Dean’s too far gone to care. He feels the alpha still and his knot swell inside, and then there’s the warm rush that always sates him - the feel of Castiel pouring alpha cum into Dean’s fertile womb. The sensation and emotional release trigger Dean’s own orgasm, further sating his need.

Being tied afterward is usually fantastic. Cas kisses and touches and dotes. They talk about everything and nothing. At some point, Dean falls asleep, and Cas falls out of him, and when he wakes again for another round, Cas will make sure he eats something and has a glass of water first.

This time, Cas is quiet, and Dean’s brain is trying to coax out from amongst the endorphins and emotions and hormones just what might be going on with his partner.

At long last, after Cas slips out of Dean while the omega is still awake, after the alpha pads to the bathroom to relieve himself and get a drink of water but doesn’t offer anything to Dean, he does speak up.

“Cas?”

“Yes, Dean?”

“You OK?”

“Hmmm? Yes, of course. Just… tired, I suppose. We should both get some sleep before…” he leaves the sentence unfinished, but Dean understands. He nods, brow still creased, and settles into his pillows.

“Dean?”

“Yeah?”

“I’ve been thinking…”

“Well, that’s never a good idea.”

But the joke goes unmentioned. “I’ve been thinking. We’re not getting any younger, and if you want pups, maybe it’s best we… that we do that. Sooner, rather than later.”

“Really bad fucking time for that right now, Cas,” is all Dean can think to say, because, Christ. Can this get any weirder? “Amara is out there, God knows where doing God knows what… getting pregnant would just make me vulnerable, as if I’m not vulnerable enough already. And we just got back from a mission to Hell that almost killed the both of us, plus Sammy. No sense bringing babies into that kind of life. I won’t do it. Wouldn’t be fair at all.”

“Yes, of course. I… didn’t mean to upset you. I’m sorry.”

“Is that what’s eatin’ you tonight? Pups? Claiming? White picket fence, the whole deal?”

“I suppose so.” All the while they’re laying with their backs to one another, which is strange but not unheard of. For millennia, Cas didn’t need to sleep at all; sometimes, he still struggles to get comfortable in a bed and will settle away from Dean if that’s the best solution. “Just seems like we ought to start moving in that direction.”

In spite of himself, and his curiosity quelled for now, Dean smiles into his pillow. “Well I’ll tell you what. We gank the Darkness, and long as we don’t get thrown right into some other fire, I’ll bare my neck to you the very next day. Consider it a… trophy, of sorts.”

Cas chuckles softly at that, but there’s a clench in Dean’s gut at the sound - again, it’s not exactly right. It’s almost like someone is trying to mimic Castiel’s laugh and isn’t getting it quite right. And there’s a tinge of something dark at the end as he says, “And then I’m gonna breed you up good, and we’ll see just what… exactly, you and I can bring into this world together.”

“Yeah.” Dean sighs. “I’m, uh. I’m gettin’ up for some water.”

He leaves the bed and pads to the kitchen. Goes through the motions of filling a water glass, drinking it down, and refilling it only to drain that one as well.

Something isn’t right.

Something  _ big _ isn’t right.

But then, he thinks as he feels the start of the fever and sweat and running of slick, maybe he’s overthinking it. Maybe it’s the hormones. Maybe it’s Cas’s hormones, at that, or the combination of the two. Maybe it’s the stress of the whole Darkness situation.

Maybe it’s a lot of things.

And it can definitely wait until after this heat.


End file.
